The long-term objective of this research continues to be elucidation of the function of proteolysis in normal lens development and in cataractogenesis. The intent of the proposed project is to determine the role of lens neutral proteinase activity in lens proteolysis and to better enumerate and characterize those enzymes which have been historically treated as a single entity: lens neutral proteinase. Bovine lens neutral proteinase preparations will be used to determine the number and association of the enzymes in the preparation, characterize the active-sites of the enzymes using specific inhibitors, determine the specificity of cleavage with peptide and lens protein substrates, investigate the mechanism underlying biphasic thermal inactivation and purify the component enzymes. To investigate the role of neutral proteinase in cataractogenesis, human lenses will be used to compare products of in vitro autolysis with peptides unique to cataractous lenses, determine the effect of adding bovine lens neutral proteinase on production of these peptides, determine the lens proteins which give rise to degraded peptides in cataract and in vitro, and measure exo- and endopeptidase activity in the normal and cataractous state. Rat lenses will be used to determine if there are low molecular weight peptides present in galactose-induced cataract comparable to those in human senile cataract and to investigate the increased thermal lability of neutral proteinase observed in the cataractous lens. If proteolysis is involved in cataractogenesis, control of degradative activity may be an alternative target for prevention of retardation of lens opacification.